(1) Field of the Invention
The present invention relates to combustion chambers used for engines and to techniques for increasing or enhancing the rate of heat flux from a combustion chamber enclosed by walls comprised of tubes or pipes.
(2) Prior Art
As shown in FIG. 1A, most combustion chambers have smooth inner walls 2 with no provisions for increasing heat transfer from a flame to the wall. In contrast, as shown in FIGS. 1B and 1C, some combustion chambers have corrugated walls 4 comprised of a plurality of tubes or pipes 6, a configuration that adds surface area, thereby increasing heat transfer. The interior of the tubes 6 typically carries a coolant such as water or hydrogen. The purpose of the tubes 6 is threefold: (1) contain the flame; (2) transfer heat from combustion gases to the coolant; and (3) contain the coolant. Thus, the walls of the tubes 6 typically must be strong, conducive to heat transfer, and capable of withstanding high surface temperatures.
A vulnerability of corrugated wall constructions is that the crowns of the walls, i.e. the portions of the wall closest to the flame, typically operate at higher temperatures than the remainder of the wall. Thus, tubular wall combustion chambers must be designed to keep the crowns of the tubes well below the melting point of the tube material. This typically requires that the tubes be oriented so that they are parallel with the hot gas flow field in the combustion chamber, because other orientations could cause the flow field to tumble as it passes over each tube. Such tumbling could cause the tube crown to overheat. This design feature means that much of the tube wall facing the flame (especially the valley between adjacent tube crowns) operates well below its maximum temperature capability.